Vasodilator drugs are the mainstay in the symptomatic treatment of ischemic conditions including angina pectoris. Patients afflicted with these conditions, especially angina pectoris, may require almost immediate therapeutic response to a vasodilator drug for relief from pain, and in some instances fright, or patients with angina pectoris may require a continuous therapeutic response to a vasodilator drug to decrease the frequency and severity of attacks. Consequently, vasodilator drugs frequently are administered sublingually because this method provides a rapid onset of therapeutic effect and accompanying immediate relief of symptoms; also vasodilator drugs are frequently administered orally because this method provides a longer duration of action for alleviating clinical symptoms and can provide prophylactic benefit
While the above methods of administration provide needed benefits, there are disadvantages associated therewith. For example, sublingually administered vasodilator drugs have a brief duration of action making it necessary for some patients to take many doses, and orally administered vasodilator drugs often are used in high doses, they are erratically absorbed into the systemic circulation, and do not provide continuous therapy.